Electronic early-learning readers are well known and have been employed for many years as teaching aids and entertainment devices. Many of the first readers developed used individual cards with words and/or graphics printed on each card. These readers use microcontrollers with software that map the contents of each card individually. The words or graphics printed on the card were associated with stored sounds and sound effects located in memory. Selection of a word or graphic printed on the card by the user would generate the associated audio sound from the interactive book reading system. The typical association would be for the reader to audibly pronounce the selected word or letter printed on the card.
Most of the first early-learning reading devices employed a panel array of membrane switches. The membrane switches which were arranged to match the content on the cards. The cards were placed on the reading device and a method of card identification was employed so that the reader knew which card was on the device. The card identification methods varied from optical card sensing through manual input. Manual input methods such as push button switches are most common in that they are less expensive to produce and reduce the complexity of the device. A common method of card or page identification is to select the card or page placed on the reader by pressing on a spot located on the card that is unique to that card. Selection of a word, letter or graphic printed on the card was accomplished by forcibly pressing down on the selected word, letter or graphic to close the membrane switch located under the card. The microprocessor would then produce the associated audio through an audible output device (e.g., speaker) in the housing of the reading device.
Many systems have been developed that use this basic technique of printed word, letter or graphic association with stored audio sound files. Texas Instruments produced many such membrane panel switch contact early-learning readers in the early 1980's. Worlds of Wonder produced such a book reading system in the mid 1980's that also used the membrane switch system. In some cases the individual cards were bound together to make small books that were placed on the interactive book reading system. The major drawback to the membrane switch system was that the printed cards or book pages needed to be very thin and flexible in order to allow the force of pressing on the card or book page to be transferred to the membrane switches located under the book. The target audience for these systems were usually toddlers and pre-school children who could not easily generate the required force to activate the membrane switches particularly when the cards were bound together to make books.
In order to overcome this drawback, new book reading systems were developed that used a handheld electronic stylus pointing pen that injected an electronic signal into a receiving panel located under the book. Sega introduced such a system in the early 1990's; other companies such as Leap Frog have also produced such handheld pen stylus readers. There are a number of major drawbacks to these pen systems. Specifically, the pens must be tethered to the system for various reasons including powering the electronics of the pen and so that the pen will not get lost. There are other drawbacks to the pen system such as the user cannot make simultaneous inputs as there is only one pointing device. Another drawback to the pen systems is that the user, typically very young, must be trained to use the pen whereas the finger selection method used by the membrane switch designs is more intuitive for the target audience.